(1) Field of the Invention
The present invention relates to a method and a device for marking the ground for an aircraft in flight, and to an aircraft provided with the device.
In particular, the invention lies in the technical field of landing lights for signaling that an aircraft is approaching a landing area, in particular at night.
(2) Description of Related Art
Such an aircraft may be authorized to fly at night and thus to land at night on a landing area.
The landing area may be prepared so as to be well lit and well defined. Individuals on the ground can then take care to keep out of the landing area so as to avoid being struck by an aircraft landing on the landing area.
Nevertheless, an aircraft may need to land on a landing area that has little or no lighting. In particular, a short landing aircraft such as a rotorcraft may land on multiple areas, and not necessarily on a runway of an airfield that is well equipped, in particular with lighting means.
Specifically, a rotary wing aircraft can land away from any base in order to bring assistance to individuals, e.g. after an accident.
Consequently, landing an aircraft on an area that is not prepared can turn out to be difficult or indeed dangerous, both for the aircraft and for individuals on the ground.
An aircraft then usually has landing lights for the purpose of lighting the target landing area. Landing lights tend in particular to enable potential dangers for the aircraft to be identified on the ground, such as obstacles that may be natural or non-natural.
A landing light emits a light beam from a halogen lamp or from a non-directional high-intensity discharge (HID) lamp. Parabolic mirrors and motors might possibly be used for collimating the light beam in a given direction.
A landing light may also comprise a light-emitting diode (LED) lamp for emitting a light beam. An optical system known as a total internal reflection (TIR) lens can be used for shaping such a light beam.
A landing light is thus restricted to projecting a light beam so that the pilot can see in the dark. On the ground, the light beam covers all of a surface that is round or oval. The light emitted at the periphery of the beam may be perceptibly diffuse and form a light halo.
Furthermore, landing lights can also be used to illuminate a landing zone in order to signal to individuals on the ground that this zone is a landing zone. The individuals then keep out of the illuminated zone in order to avoid being impacted by an aircraft that is landing.
Nevertheless, in an area that presents high ambient brightness, an individual may find difficulty in accurately identifying the zone that is illuminated by the aircraft.
For example, on particular landing zones where numerous vehicles are present, the lights of those vehicles can make it difficult to identify the zone that is being illuminated by an aircraft. By way of illustration, numerous vehicles may be involved in a given area during a rescue mission. Under such circumstances, it can be difficult to identify the zone that is being illuminated by an aircraft while it is landing.
Present-day helicopters are essentially identified by the noise given off by such helicopters. The lighting provided by a landing light can indeed be used to warn individuals that a helicopter is in an approach stage, but that solution is not always satisfactory.
An object of the present invention is thus to propose a method enabling an aircraft to mark accurately the landing zone being targeted by the aircraft.
Documents CN 102998885, CN 104036475, DE 10 2013 009 803, and WO 2015/019208 are mentioned by way of illustration, but they do not form part of the technical field of the invention, and they do not give any teaching on how to solve the above-described problem.
Documents EP 2 433 869, US 2003/0058653, US 2010/0302072, and U.S. Pat. No. 4,916,445 are also known.